Responses and reuse
Delivery & performance
Distinguish browser and CDN caches, freshness, origin fetches and revalidation without assuming every response is stored.
- concept
CDN
Understand how a CDN serves nearby edge responses, when it contacts origin, and why not all content is cached.
Explore the idea - concept
Browser cache
Learn when a browser can reuse a response, revalidate it, or must fetch it again under HTTP caching rules.
Explore the idea - concept
HTTP Cache-Control
The HTTP Cache-Control response field describes constraints on storage and reuse of a response.
Explore the idea - concept
ETag and conditional requests
An HTTP ETag is an opaque representation validator.
Explore the idea
Compare the browser, edge cache and origin separately. Freshness directives and request conditions decide whether stored content may be reused.